To be precise, it should be "UL" and "VDE": UL mark is the United States as well as North America's recognized safety certification mark, affixed with this mark of the product is equivalent to obtaining the safety and quality credibility of the card, and its degree of credibility has been accepted by the majority of consumers. The degree of credibility has been accepted by the majority of consumers. Therefore, the UL Mark has become a special passport for products (especially electromechanical products) to enter the U.S. and North American markets. UL Mark is divided into 3 categories, namely, Listing, Classification and Recognition Marks, and the main component of these marks is the pattern of UL, which are registered trademarks. Separately applied to different service products, is not common. 1, listing UL listing mark on the product is to indicate that the manufacturer of the entire product samples have been tested by UL, and comply with the applicable UL requirements. 2、Classification Products with this mark have been evaluated for their limited scope of hazard or suitability for use. 3, meta/component certification In order to speed up the evaluation of the product or system, and save money, for the composition of incomplete or limited performance of the component, for later use in UL listed or classified products or systems in the product, can be meta/component certification. The use of UL listed components in any final product does not imply that the product itself is UL listed. VDE is a renowned German testing organization and is directly involved in the development of German national standards. Like UL, the VDE mark can only be used by VDE companies authorized to use the VDE mark. Most people's understanding of VDE stays in the certification of electrical components, in fact, VDE testing in addition to the traditional electrical components, wires and cables, plugs and other certifications can also be issued in addition to the EMC logo and VDE-GS logo. Now more and more equipment on the computer, energy consumption is also increasing, without a powerful power supply, there is a risk of damage to the motherboard, hard disk and other components, shortening the normal service life of the computer. Currently on the market a wide variety of power supplies, from tens of dollars to hundreds of dollars, how to choose a quality power supply, the main thing to look at how its safety certification. Usually, the more certified items, the more reliable the quality of the power supply. When we buy, we should try to choose such a power supply. Power supply certification program 1 CCEE certification CCEE is the English abbreviation of the China Certification Council for Electrical Product Safety, which is the only electrical product safety certification body in China. CCEE certification is a mandatory certification standard for electrical products, that is, wherever electronic products are sold on the market in our country must be mandatory to pass the certification, otherwise they can not be sold in the market. CCEE certification for the green pattern on a white background, by the symbols representing China and the Great Wall. CCEE certification is a green pattern on a white background, composed of symbols representing China and the Great Wall, so it is often also known as the Great Wall certification. 2 FCC certification FCC is a certification of electromagnetic interference. Power supplies generate strong electromagnetic interference internally when they are in operation. If it is not shielded, it may affect the monitor, motherboard and other electrical equipment, and even bring harm to the human body. Therefore, there are strict international regulations on electromagnetic interference, the general standards have FCC-A industrial standards and FCC-B civil standards, only in line with the latter power supply is safe and harmless. 3 UL certification UL (Underwriters Laboratories) is the United States of America's most authoritative, non-profit civil safety testing organizations, it is mainly on a variety of equipment, systems and materials for safety testing and inspection, to confirm whether there is a danger to life and property, and will be published test results. UL published hundreds of standards, most of which were adopted by the ANSI (American National Standards Institute). In general, UL standards can be divided into: requirements for the structure of the product, requirements for the raw materials used in the product, requirements for the components used in the product, requirements for test equipment and test methods, requirements for product marking and instructions. Now UL certification has become one of the world's most stringent certification. 4 CSA certification CSA is the abbreviation of the Canadian Standards Association, which is the first Canadian non-profit organization specializing in the development of industrial standards, but also one of the world's most famous certification bodies. In the North American market for the sale of electronic, electrical and other products have to obtain the CSA safety aspects of the certification. The standard is mainly on products, processes, materials, testing methods, services, security and materials and other aspects of the provisions made. 5 CE certification CE is the "European Union" Latin abbreviation, it is the implementation of the European Union to prove that the product meets the specified requirements of the qualified product marking. CE marking is a mandatory pass, but also one of the basic certification standards for the production and manufacture of power supplies, which requires that power supply products must be protected to protect the user's health and safety and in line with the environmental protection of the basic requirements. It requires that power supply products must protect the health and safety of users and meet the basic requirements of environmental protection. Assessment of power supply indicators Generally speaking, the safety certification of power supplies to Germany based on the 1EC-380 standard developed by the VDE-0806 standard is the most stringent, China's national standard is GB4943-1995 "information technology equipment (including electrical equipment) safety". Regardless of which country to develop standards, mostly from the creepage distance, electrical strength, leakage current, temperature and other aspects of the strict provisions. Creepage distance requirements: creepage distance refers to the shortest distance measured along the insulating surface between the two conductive devices or conductive devices and equipment interface between the UL, CSA and VDE safety standards emphasize the creepage distance of the safety requirements, which is designed to prevent the device or the device between the device and the ground to prevent ignition and thus threaten personal safety. Requirements for electrical strength: Between the AC input line or between the AC input and the chassis from zero voltage to AC 1500V or DC 2200V, no breakdown or pull arc is qualified. Requirements on leakage current: UL and CSA both require that exposed, non-electrified metal parts should be connected to earth. Leakage current is measured by connecting a 1.5kΩ resistor between these parts and the earth to measure the leakage current. The leakage current of a switching power supply should not exceed 3.5mA at 260V AC input. Temperature requirements: Safety standards place great importance on the temperature requirements of electrical appliances, and also require materials to be flame retardant. For switching power supplies, the internal temperature rise should not exceed 65°C. If the ambient temperature is 25°C, the temperature of the power supply's components should be less than 90°C. Power supplies that do not meet safety standards at the beginning of the user does not have any direct adverse effects, but after a long time, due to humid air and dust may lead to high-voltage areas of short-circuit, not only cause damage to the power supply itself, but also seriously affect the power grid, thus adversely affecting other electrical appliances. Electromagnetic interference requirements: the international standard FCC-A (industrial standards), FCC-B (civil standards), the power supply should comply with civil standards. Electromagnetic interference is divided into conducted interference and radiated interference. Conducted interference spreads through the power line, the frequency is 30MHz or less, mainly interfering with the audio frequency band. As the computer switching power supply has a metal shell for shielding, so the power supply interference is more reflected in the conductive interference. The size of the conducted interference is an important measure of the quality of the computer power supply standard, which includes two aspects of the meaning: one is to prevent electromagnetic interference on the power grid through the power supply itself electromagnetic interference into the grid, affecting the host system to work properly; the second is to prevent the host itself electromagnetic interference into the power grid, affecting other appliances. We may have such experience in our daily work, when the microcomputer is turned on, its nearby electrical appliances such as TV, stereo, etc. can not be used normally, which is the impact of conduction interference. Finally, I hope that this article can give you friends to buy power supply to help, so as not to save a few dozen dollars and cause the loss of thousands of dollars. Power supply safety certification Safety standards to protect the user's life and property safety as a starting point, insulation of raw materials, flame retardant and other aspects of the strict provisions. Products in line with safety standards, not only require the product itself meets the safety standards, but also for the production of manufacturers also require a more complete safety production system. In these standards, based on the German 1EC-380 standard developed by the VDE-0806 standard is the most stringent. China's national standard is GB4943-1995 "information technology equipment (including electrical equipment) safety". Power supply meets the above standards its safety is guaranteed. Power supply meets the safety standards of a country and get the certificate issued by its legal department, such as obtaining the certificate issued by UL organization, it is called obtaining UL certification. China's safety certification organization is CCEE, regardless of the country's safety certification, are on the creepage distance, electrical strength, leakage current, temperature and other aspects of the strict regulations. 1, safety regulations: safety regulations is also known as the safety standard specifications, safety regulations for the manufacture of devices and electrical components have a clear statement and guidance to provide a safe and high-quality products to end-users; its purpose is mainly used to prevent electric shock, energy hazards, fire, mechanical and heat hazards, radiation hazards, chemical hazards, and other hazards, and to ensure the safety of the product. The purpose is to prevent electric shock, energy hazards, fire, mechanical and heat hazards, radiation hazards, chemical hazards, etc. from harming the human body. Generally, each country can establish its own national electrical safety standards, but most power supply manufacturers use IEC, VDE, UL, CSA safety standards as a solution to the safety needs of UL and VDE safety standards are fundamentally different, UL specifications are more focused on the prevention of fire hazards, while the VDE specifications are more about the safety of the operator, for the power supply, the VDE specifications are more about the safety of the operator. VDE is the most stringent electrical safety standard for power supplies. Safety Policy: Zero defects in high voltage and grounding tests. 2. Power Supply Structure Safety Requirements (1) Spacing Requirements UL, CSA and VDE safety specifications mandate specific spacing requirements between active components, and between active components and fixed metal components, spacing requirements include spacing distance and distance along the surface, spacing distance is also known as the clearance distance in VDE, and separation distance in UL. Separation distance, VDE standard specification along the surface of the distance in the UL standard specification is called separation distance. Space distance (Creepage distance): between two conductive components or conductive components and the interface between the shortest straight-line distance measured by air separation; along the surface distance (clearance): along the insulating surface measured between two conductive components or conductive components and the interface between the shortest distance between the object. (2 dielectric test withstand (dielectric test withstand) When the device on the rated voltage of 250Vac or less, in the UL and CSA standard specifications need to be done to the input to the output and input to the ground side of the high-potential isolation test (HI-POT isolation test) (3 leakage current measurement (leakage c
Leakage c